CSDP Plus Servo Drive User Manual

The speed reduction ratio is the ratio of revolutions of the system to
the motor. If the system make one revolution when the motor makes
five revolutions, the speed reduction ratio is 5. If the system make five
revolutions when the motor revolves once, then the speed reduction
ratio is 0.2.
The numerator and denominator of the electronic gear can be
calculated as below.
(SEt-36) Numerator = Number of pulses of the encoder × Speed reduction
ratio
(SEt-37) Denominator = Number of pulses per a revolution of the motor
In the case of a ball screw whose speed reduction ratio is 1 and the
number of pulses of the encoder per one revolution is 5000, if the
controller approves 1000 pulses for the servo drive to make the motor
finish one revolution, the numerator of the electronic gear is 5000 and
the denominator is 1000.
The ball screw finishes one revolution with 1000 pulses and thus a ball
screw with 10 mm pitch can move 10 with one pulse command.
ATTENTION
As the denominator increases, the resolution becomes
higher. But the following expression should be satisfied.
Pulse of the encoder ✕ Speed reduction ratio ✕ 4 ≥
Denominator
In this case, the maximum denominator is 20000.
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